C Programming Questions and Answers – Variable Names

C Programming Questions and Answers – Variable Names – 1

This section on C interview questions and answers focuses on “Variable Names”. One shall practice these interview questions to improve their C programming skills needed for various interviews (campus interviews, walkin interviews, company interviews), placements, entrance exams and other competitive exams. These questions can be attempted by anyone focusing on learning C Programming language. They can be a beginner, fresher, engineering graduate or an experienced IT professional. Our C Interview questions come with detailed explanation of the answers which helps in better understanding of C concepts.
Here is a listing of C interview questions on “Variable Names” along with answers, explanations and/or solutions:

1. C99 standard guarantees uniqueness of ____ characters for internal names.
a) 31
b) 63
c) 12
d) 14

2. C99 standard guarantess uniqueness of _____ characters for external names.
a) 31
b) 6
c) 12
d) 14

3. Which of the following is not a valid variable name declaration?
a) int __a3;
b) int __3a;
c) int __A3;
d) None of the mentioned

4. Which of the following is not a valid variable name declaration?
a) int _a3;
b) int a_3;
c) int 3_a;
d) int _3a

Explanation:Variable name cannot start with a digit.
5. Variable names beginning with underscore is not encouraged. Why?
a) It is not standardized
b) To avoid conflicts since assemblers and loaders use such names
c) To avoid conflicts since library routines use such names
d) To avoid conflicts with environment variables of an operating system

6. All keywords in C are in
a) LowerCase letters
b) UpperCase letters
c) CamelCase letters
d) None

7. Variable name resolving (number of significant characters for uniqueness of variable) depends on
a) Compiler and linker implementations
b) Assemblers and loaders implementations
c) C language
d) None

Explanation:It depends on the standard to which compiler and linkers are adhering to.
8. Which of the following is not a valid C variable name?
a) int number;
b) float rate;
c) int variable_count;
d) int $main;

Explanation:Since only underscore and no other special character is allowed in a variable name, it results in an error.
9. Which of the following is true for variable names in C?
a) They can contain alphanumeric characters as well as special characters
b) It is not an error to declare a variable to be one of the keywords(like goto, static)
c) Variable names cannot start with a digit
d) Variable can be of any length

10. Which is valid C expression?
a) int my_num = 100,000;
b) int my_num = 100000;
c) int my num = 1000;
d) int $my_num = 10000;

11. What is the output of this C code?

#include <stdio.h>
int main()
{
printf(“Hello World! %d \n”, x);
return 0;
}
a) Hello World! x;
b) Hello World! followed by a junk value
c) Compile time error
d) Hello World!

12. What is the output of this C code?

#include <stdio.h>
int main()
{
int y = 10000;
int y = 34;
printf(“Hello World! %d\n”, y);
return 0;
}
a) Compile time error
b) Hello World! 34
c) Hello World! 1000
d) Hello World! followed by a junk value

13. Which of the following is not a valid variable name declaration?
a) float PI = 3.14;
b) double PI = 3.14;
c) int PI = 3.14;
d) #define PI 3.14

14. What will happen if the below program is executed?

#include <stdio.h>
int main()
{
int main = 3;
printf(“%d”, main);
return 0;
}
a) It will cause a compile-time error
b) It will cause a run-time error
c) It will run without any error and prints 3
d) It will experience infinite looping

15. What is the problem in following variable declaration?
float 3Bedroom-Hall-Kitchen?;
a) The variable name begins with an integer
b) The special character ‘-‘
c) The special character ‘?’
d) All of the mentioned

16. Comment on the output of this C code?

#include <stdio.h>
int main()
{
int ThisIsVariableName = 12;
int ThisIsVariablename = 14;
printf(“%d”, ThisIsVariablename);
return 0;
}
a) The program will print 12
b) The program will print 14
c) The program will have a runtime error
d) The program will cause a compile-time error due to redeclaration

17. Which of the following cannot be a variable name in C?
a) volatile
b) true
c) friend
d) export
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